Once the tool machine has been set up for a particular operation the accuracy of the depth of cut depends on maintaining a constant distance between the cutting edge and a fixed point on the tool holder. Where the cutting tool uses an insert special steps have been taken in the prior art to assure the accuracy and constancy of the depth of cut. The steps include forcing the cutting insert to abut the same surface on the cutting tool holder at all times. Clamp means of various kinds are used to hold the cutting tool insert against the abutting means.
The clamping arrangements, however, complicate the tools, take up valuable space, make the tooling more expensive and also add to the difficulties of using the inserts in the tools. Accordingly, in recent years tool insert systems have been provided which do not require clamping. Such tool insert systems, however, are not amenable to precision usage. The distance that the cutting inserts in such systems extend beyond the holders varies with characteristics, such as the feed rate and the material being cut.
The prior art inserts that are held without clamping means are held either by spring forces such as that shown in the system disclosed in U.S. Pat. No. 3,785,021 or the insert is held by the geometry of the insert in relation to the geometry of the holder. This type of self-gripping is shown in Belgian Pat. No. BE 853,475. It is also shown in Israel Patent Application No. 58862 in which there is a spring element which secures the insert from going out of the seat in addition to the wedge-like geometrical configurations that retain the insert in the tool holder.
When using spring forces for maintaining the insert in the holder without clamping means as disclosed in the U.S. patent, it is possible, theoretically, to maintain the distance that the insert extends beyond the holder constant. In practice, however, the spring element in the body of the holder which holds the cutting insert in place is the weak point of the tool. While working with the tool, the cutting forces negatively affect the stability of the clamping system such that it is not possible to make true precision cuts.
It is definitely not possible to make precision cuts with the prior art systems which use geometrical configuration for retaining purposes. More particularly the geometrical configuration in the prior art systems use recesses defined by jaws in the tool holder. The jaws are at a first angle and abut clamping surfaces on the inserts which are at slightly larger angles. Thus as the cutting forces act on the cutting insert during the cutting operation the insert is forced further into the jaws until equilibrium is reached and the insert is locked in place. However, since the equilibrium point can vary, it has not been possible to use such tools for precision work. Accordingly there is a long-felt need for cutting inserts that are maintained in the tool holders by the geometrical configurations and that can be used for precision work.
It is an object of the present invention to provide a new and improved precision groove cutting tool system in which the above-referred to disadvantages are substantially reduced or overcome.